“We welcome that because they will help us to prepare,” she said. “WHO is contacting each of the vaccine manufacturers and requesting from them information on their current plans to modify their vaccines,if they have any preliminary data,and the timeline for the scaling up and implementation of the modifications.”
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WHO is looking to play a coordinating role,as it does with seasonal influenza vaccines,to ensure any decision to change the immunisations is based on the recommendations of global experts,manufacturers and regulatory authorities,Henao-Restrepo said.
Global coordination
“In the best interest of the planet,a coordinated approach in the decision-making process is the best,” she said.
Some experts thought an updated shot would be necessary to corral the Beta variant because of its ability to evade protection. But that strain never became dominant globally and the current vaccinations have been shown to significantly avert severe infection and deaths.
Although antibody levels decline in the months after an infection or vaccination,their ability to neutralise coronavirus variants has been shown to improve over time. What’s more,studies have found that a third dose some six months after the second can bolster levels of these better-quality antibodies,making boosters an important weapon to fight Omicron.
“I don’t think we should get all excited about some sort of Omicron-specific vaccine because,so far,that’s not what we’ve seen as being the best thing to fight against it,” said Deborah Cromer,head of the infection epidemiology and policy analytics group of the University of New South Wales’ Kirby Institute in Sydney. “We’ve seen that the wild-type vaccines are fine and are doing a good job.”
Escaping recognition
The Omicron variant has 30 or more changes in the spike protein,half of which are in the area that binds to the enzyme that the coronavirus targets to enter cells and cause an infection. Mutations there can make the pathogen less recognisable to antibodies.
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It’s possible SARS-CoV-2 will eventually accumulate enough mutations to escape antibody detection completely and warrant the need for booster shots with a different formulation,said Jonathan Abraham,an assistant professor of microbiology in the Blavatnik Institute at Harvard Medical School and an infectious disease specialist at Boston’s Brigham and Women’s Hospital. “But at this point,there’s no evidence to say that the virus has found a perfect solution that allows escape.”
Abraham and colleagues studied mocked-up coronavirus versions,called pseudoviruses,with mutations in the pathogen’s receptor binding domain to test the effectiveness of vaccine-induced and therapeutic antibodies. Resistance was detected when seven mutations were found,his research published on Thursday in the journalScience found.
It’s still too early to say whether Omicron – with 15 mutations in the receptor binding domain – will require vaccines to be updated,Abraham said. “But all evidence is pointing in that direction,meaning that if we were asking ourselves that question with Beta,we should definitely be asking ourselves that question even more urgently with Omicron.”